Reinforced exhaust valves Opel Z16LER Z18XER A18XER

Opel engines covered

The Z16LER is the 1.6 litre 16-valve turbo of the Opel Corsa D; the Z18XER and A18XER are the naturally aspirated 1.8 litre engines of the same family, fitted to the Astra H and J, Zafira B and C, Insignia and Mokka.

These engines carry 8 exhaust valves, two per cylinder: 55355572 (6 41 392) on the Z16LER, 24405815 (6 41 391) on the Z18XER and A18XER, with a 27.5 mm head, a 5.0 mm stem and a 113.2 mm length.

SUPERTECH reinforced exhaust valves

On the turbocharged Z16LER, the metal of an exhaust valve head goes beyond 1,000 °C, against 760 to 870 °C on a naturally aspirated 1.8. About 75 % of that heat leaves through the seat and 20 % through the guide. An EV8 family steel holds 550 MPa at 600 °C but only 300 MPa at 800 °C: with more boost, the head overheats, distorts and the seat loses its seal.

SUPERTECH makes this valve in Inconel, a nickel-based superalloy that keeps 860 MPa at 730 °C and 554 MPa at 815 °C, about 85 % more than the reference steel near 800 °C: the right choice for a Z16LER running raised boost.

Exhaust valve technical specifications

GEVI-3320S-8 has a 27.5 mm dished head, a 4.95 mm stem, a 113.15 mm length and a single groove.

Valve fitting

The single groove of the GEVI-3320S requires the KPR-5.0-7S single groove collets in place of the original collets.

At standard size, the 27.5 mm head bears on the factory exhaust seats, simply recut.

Valve stem seals and guides are chosen for the 5 mm stem of these engines.

Technical guide

Our brand

SUPERTECH Performance, a Californian maker of competition valves for more than thirty years, offers one single groove Inconel exhaust valve at standard size for the Z16LER, Z18XER and A18XER.

How to choose

A single version is offered for these engines:

When reinforced valves become necessary

• Z16LER with raised boost (Inconel version)
• Higher lift camshafts
• Track use
• Cylinder head rebuild with burnt or distorted exhaust valves

Vehicle compatibility

OEM part number (exhaust valve): 55355572 (6 41 392) (Z16LER) ; 24405815 (6 41 391), 55572521 (6 41 099) (Z18XER, A18XER)

Don't forget the inlet valves

A Z16LER or Opel 1.8 cylinder head on the bench is the occasion to renew the inlet valves and the valve stem seals as well.